I set up our initial website using dotnetnuke 3.  We have a sister company and we're transferring the domain so that we will manage their website too.

My confusion is, and excuse me if this is really simple, how to set up dotnetnuke so I can have two distinct domain names utilising the dot net nuke portal.

Lets say we currently have www.site1.co.uk set up.

I've gone into dot net nuke on our website and added a PARENT portal, with our new domain name www.site2.co.uk.

I've set the domain names name servers to our ISP.

Beyond that, I'm not sure what to do.  How can the domain name know where to go?  I've tried setting up a domain alias on our website for the new domain name (ie so site2 forwards to site1, hoping that dnn would then recognise the domain name and display as required), but all this does then is forward site2 to the standard site1 website.

I'm at the point where I've had to install dnn on the second site as well as the first, clearly that's stupid and totally against the whole point of a portal system, but for the life of me I cannot seem to find anything in the help that tells me what to do outside of dot net nuke in order to get this working.

Apologies again if I'm being a complete idiot, any help appreciated!